Saturday, 19 January 2013

Black Spud Confusion —

Back in 2010 I posted here about the black potato "Négresse" which I grow every year. The article kicked off some speculation about naming confusion between Négresse, the very similar Congo, and a third potato, Vitelotte...
Well grown examples (if I do say so myself) of the blue-black fleshed potatoes Congo(left) and Négresse.
Having grown Congo and Négresse together for a couple of years now, I can confidently say that they are not the same variety. Appearance, eating qualities, and resistance to tuber blight are similar, but...

—Négresse has a squarer shape than Congo (most obvious on fully mature tubers).
—Négresse tuberises slightly earlier (or at least gives more crop by early July when mine were killed by blight last year).
—Their foliage is noticeably different.
—Négresse has a shorter dormancy period.

I have said previously that I suspected Negresse was truly day-length sensitive (like oca); the plants will continue to grow without naturally dying back, until the first frost. Actually I now realise that very small tubers are formed by mid summer, so the plant is not day length sensitive. But they do need a very long growing season to reach the size of those in the top photo.

Here are my lazy beds in June last year, complete with authentic blight blackened foliage...
I was expecting to find no tubers at this time of year, but I was pleasantly surprised to find small tubers had already formed.

And then there is Vitelotte. Wikipedia says this is synonymous with Négresse. So do seed merchants Thompson and Morgan who are selling them as micropropagated mini tubers this year. Others say they are clearly different, so who knows. I certainly get larger tubers than those shown on the T & M site.

Changing the subject, an annoying problem with all these black potatoes is finding the well camouflaged tubers in the soil at harvest time. Missed tubers result in persistent volunteers which can be real pests amongst a following crop. No such problem with this new (as yet unnamed) variety...
...which has spectacularly prominent fluorescent pink skin and flesh!
Sunglasses not included.